1. Field of the Invention
The invention relates to a heat-dissipating device and a housing thereof, and more particularly to an axial fan having an increased intake airflow rate without modifying the assembling conditions with other elements so as to greatly enhance the heat-dissipating performance of the fan, and a housing for the fan.
2. Description of the Related Art
A typical electrical product usually includes electrical elements positioned in a closed housing in order to prevent the electrical elements from being contaminated with particles in the air. However, since the electrical element (such as a central processing unit (CPU) or circuit board) raises its temperature during operation, the element tends to be consumed and the lifetime thereof tends to be shortened if the element is continuously kept at the high-temperature condition. Thus, a fan is typically disposed in the housing to dissipate heat to the outside in order to prevent the electrical element from failing.
As shown in FIG. 1, a conventional fan 1 is mainly composed of a fan housing 11 and an impeller 12. When the fan is operating, a motor may be used to drive the impeller 12 to rotate and to produce air streams flowing toward the electrical element in order to dissipate the heat generated from the electrical element. The fan housing includes an air inlet and an air outlet in communication with the air inlet via a central, cylindrical air passage 11a. The air streams caused by the impeller 12 may freely flow into and out of the fan housing via the air passage. Furthermore, a plurality of tapered portions 13, through which the air streams may smoothly flow into the air inlet side, are provided at the corners on the air inlet side of the air passage. In addition, a plurality of screw holes 14 is formed at four corners of the fan housing such that the fan may be mounted to a frame of an electrical apparatus (i.e., a computer) via the screw holes 14.
However, due to the restriction in the dimension of the rectangular fan housing of the conventional fan, the air passage at the lateral side has to be reduced. The optimized design in the shape of the blade based on the curve of the air passage is also restricted, and the space and material of the fan housing are also wasted. Besides, due to the restriction in the construction of the fan housing, air may be taken into the fan only in the axial direction. However, it only can achieve very limited improvement effect in the increased intake airflow rate by doing so.